If it draws the design current for 12 seconds and then drops it sounds like a safety in the controller kicks in.
From: Roger L <rogerlov@ix.netcom.com>
To: electricboats@yahoogroups.com
Sent: Thursday, July 11, 2013 8:24 AM
Subject: Re: [Electric Boats] Wrong prop or engine?
Clever idea !
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----- Original Message -----From: Paul DillonSent: Thursday, July 11, 2013 7:47 AMSubject: Re: [Electric Boats] Wrong prop or engine?How hard would it be to swap the props?Paul
On 2013-07-11, at 9:07 AM, "marcdrachten" <mevanderkuur@gmail.com> wrote:
Hi,
Recently I fitted our sailboat, a Hood 32, with a 2kW mastervolt podmaster. Just like they did on a sistership.
On the sistership the system runs fine, on my boat the boat doesn't reach hullspeed where the sistership does. And the power used from the battery is well below of what it should be at full power. Now the discussion is, is it the prop, the motor or the controller that's faulty.
The supplier expects the prop to be faulty, I think it's the motor. Any thoughts on how I can determine where the error lies without going into demounting and reinstalling the engine and prop?
The engine draws 83 amps @ 27 V for 12 secs (system design) and then drops to 55 amps, measured on the battery. When I measure between the controller and the motor it draws 110 amps for 12 secs and then drops to 85 amps. I didn't actualy measure it, but I assume since amps are higher, voltage should be lower between the controller and motor. For as far as I can tell the motor doesn't reach it maximum rpm.
What does this say about the prop or the motor?
I would say:
If the prop is too light, rpm should be high, amps lower than expected and boatspeed also lower than expected, what about voltage?
If the prop is too heavy, rpm should be low, amps high and voltage normal, boatspeed unsure.
What are your thoughts?
24v system with 5kW lithium battery
24v DC PM podmotor 2 kW with folding prop
Sistership has same config except the batteries are AGM batteries.
Marc
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